A conventional magnetic refrigerator is disclosed in U.S. Pat. No. 6,668,560. As shown in FIGS. 1 and 2, in accordance with the conventional magnetic refrigerator, while a heat transfer fluid 17 entering into a cold side inlet port 22 through a cold side inlet pipe 21 flows to a hot side outlet port 34, the heat transfer fluid 17 absorbs a heat generated by a magnetocaloric effect of a magnetocaloric material 12 having a magnetic field applied thereto and exits to a hot side outlet pipe 33 through a hot side outlet ports 34 to cool the magnetocaloric material 12. A hot side sequentially passes the hot side outlet pipe 33, a valve 71, a pump 60, and a hot heat exchanger 62 and flows into a magnetic heat exchange compartment 13. In a hot side inlet pipe 31, the hot side is divided into the hot side inlet pipe 31 and a cold side outlet port 23, and meets a cold side at a cold side outlet pipe 24 and proceed to a valve 74. When the hot side moves from a hot side inlet port 32 to the cold side outlet pipe 24, the hot side is cooled by passing the magnetocaloric material 12 already cooled by the hot side. The cold side that has passed through the valve 74 passes a cold heat exchanger 63 and flows to pipes 83 and 21 to repeat a cycle (a detailed description is omitted. See U.S. Pat. No. 6,668,560 for omitted reference numerals).
As described above, since the conventional magnetic refrigerator comprises twelve magnetic heat exchange compartments, four valves 71, 72, 73 and 74 and more than 24 pipes, it is difficult to manufacture the conventional magnetic refrigerator.
Moreover, since a single heat transfer fluid is circulated to serve as the hot side and the cold side simultaneously, that is, since the hot side enters at the hot side inlet port 32 to pass the cold magnetocaloric material (See FIG. 2) and cooled into the cold side to exit through the cold side outlet pipe 24, a efficiency of a heat exchange is degraded. It is known from this fact that when the heat transfer fluid having a temperature lower than that of the hot side entering the hot side inlet port 32 enters the hot side inlet port 32 and passes the cooled caloric material, the heat transfer fluid having a temperature lower at the cold side outlet pipe 24 may be flown out to improve the efficiency of the heat exchange.
In addition, since amount of the heat transfer fluid passing through the hot side cannot be controlled, a heat of the magnetocaloric material cannot be cooled promptly, thereby degrading the efficiency of the heat exchange.
On the other hand, when the magnetocaloric material passes through the magnetic heat exchange compartment, the magnetocaloric material is in direct contact with the heat transfer fluid, thereby causing an oxidation.
Moreover, the magnetocaloric material of a power type is lost through an exit (a mesh) when passing through the magnetic heat exchange compartment and the magnetocaloric material may be accumulated at the exit according to a strength of the heat transfer fluid to block a flow thereof.